autocomplete search form with multiple input php mysql

Hi Guys I have this search from that takes a search term matches it with a table.field and in php it searches all matching data. I want to add autocomplete to it, can anyone PLEASE assist?

Here is the HTML FORM

<form action="'.$_SERVER['REQUEST_URI'].'" method="post">   
    <input type="text" id="searchThis" name="searchThis"  placeholder="search" value="" size="14" />
        <select name="searchItems" id="searchItems"> 
        <optgroup value="Vehicles" label="Vehicles">Vehicles 
            <option value="vehicles.Make">Make</option>
            <option value="vehicles.model">Model</option>
            <option value="vehicles.RegNumber">Registration Number</option>
            <option value="vehicles.licenseExpireDate">License Expire Date</option>
        </optgroup>
        <optgroup value="Owners" label="Owners">Clients
            <option value="owners.OwnerName" label="" >Name</option>
            <option value="owners.mobile">Mobile Number</option>
        </optgroup>
        </select> 

    <input type="submit" id="doSearch" name="Search" value="Search" />
    </form>
    <ul id="result">
    </ul>

There is the JS

<script src="js/jquery-1.8.0.min.js" type="text/javascript"></script>
<script type="text/javascript">
 var $j = jQuery.noConflict(); 

(function($j){

 $j(document).ready(function (){

    $j("#searchThis").keyup(function() 
    { 
    var searchThis = $j('#searchThis').val();
    var searchItems = $j('#searchItems').val();
    var dataString = {'searchThis': searchThis,'searchItems':searchItems};
    if(searchThis!='')
    {
        $j.ajax({
        type: "POST",
        url: "doAutocomplete_search.php",
        data: dataString, 
        dataType: "html",
        cache: false,
        success: function(data)
        {
        $j("#result").html(data).show();
        }
        });
    }return false;    
    });

    $j("#result").live("click",function(e){ 
        var clicked = $j(e.target);
        var name = clicked.find('.name').html();
        var decoded = $j("<div/>").html(name).text();
        $j('#searchThis').val(decoded);
    });

    $j(document).live("click", function(e) { 
        var clicked = $j(e.target);
        if (! clicked.hasClass("search")){
        $j("#result").fadeOut(); 
        }
    });

    $j('#searchid').click(function(){
        $j("#result").fadeIn();
    });    

});

})($j);

And the PHP

function implement($cxn,$searchThis, $field) {
$show = "";

//Item to be searched
$srchThis = strip_tags(trim($searchThis));
//[0]= table , [1]=field    to search

$srchStack = explode('.',$field);
    $gtData = "SELECT * FROM ".$srchStack[0]." WHERE ".$srchStack[1]." like '%|{$srchThis}|%'";
         //or die(mysqli_error($cxn))
        if($selectc = mysqli_query($cxn,"SELECT * FROM {$srchStack[0]} WHERE {$srchStack[1]} LIKE '{$srchThis}%' OR {$srchStack[1]} LIKE '%{$srchThis}%'")) { 
            $srchData = array();
        $rows = mysqli_fetch_row($selectc);
        echo $rows;
            //if() {, MYSQL_ASSOC
                //echo var_dump($srchData);
                $show .= '
                <table style="border:2px solid #0000">';
                //foreach($srchData as $fields=>$data) {
                for($s=0; $s < $rows && $srchData = mysqli_fetch_assoc($selectc);$s++) {
                    if($srchStack[0] == 'vehicles' && $fields == 'RegNumber') {
                        $dataItem = $data;
                        $editTbl = 'Vehicles';
        $link = 'href="index.php?list=vehicles&&tbl='.$srchStack[0].'&&item='.$dataItem.'"';
                    } elseif($srchStack[0] == 'vehicles' && $fields == 'Make') {
                        $dataItem = $data;
                        $editTbl = 'vehicles';
        $link = 'href="index.php?list=vehicles&&tbl='.$srchStack[0].'&&item='.$dataItem.'"';
                    }

                    $show .= '<tr><td><a '.$link.'>'.$data.'</a></td></tr>
                    ';  
                }
                $show .= '</table>';

                return $show;
        } else {
            $show .= "There are no entries in the database...<br>".mysqli_error($cxn);

            return $show;
        } 
    //}

}

echo implement($cxn, $_POST['searchThis'], $_POST['searchItems']);


$cxn->close();