As long as your input is sanitized, you can use implode to prepare the statement.
$stmt = 'SELECT * FROM `table` ';
$stmt .= "WHERE title = '" . implode("' OR title = '", $titles) . "'";
Result
SELECT * FROM `table` WHERE title = 'Dr.' OR title = 'Ms.' OR title = 'Mr.'
See a demo
You can alternatively use IN:
$stmt = 'SELECT * FROM `table` ';
$stmt .= "WHERE title IN ('" . implode("', '", $titles) . "')";
Result
SELECT * FROM `table` WHERE title IN ('Dr.', 'Ms.', 'Mr.')
You need to fix your GROUP BY; you're not using it correctly.
If you want to sort the order of your titles, you can try:
ORDER BY
CASE
WHEN title = 'Dr' THEN 1
WHEN title = 'Ms.' THEN 2
WHEN title = 'Mr.' THEN 3
ELSE 4
END