How to handle special charaters in PostgreSQL JSON's like_regex statement

I have some trouble in using jsonb's like_regex statement. I usually use the statement for my jsonb's query statement, that is:

jsonb @? jsonpath

The query condition is transfered from the front as a json statement, just like:

{
"fname=":"Tiger",
"flocation~*":"Shenzhen, China, (86)"
}

I write a function to parse the json statement to the jsonpath statement, like:

jfilter:='{"fname=":"Tiger","flocation~*":"Shenzhen, China, (86)"}'::jsonb;
cur refcursor;
vkey text;
vval text;
vrule text;

open cur for select * from jsonb_each(jfilter);
loop
    fetch cur into vkey,vval;
    if found then
        if strpos(vkey,'=')>0 then
            ...
            vrule:=concat('@.',vkey,vval::text);
            ...
        elseif strpos(vkey,'~*')>0 then
            ...
            vrule:=concat('@.',vkey,' like_regex ',vval::text,' flag "i"');
            ...
        end if;
    else 
        exit;
    end if;
end loop;
close cur;

And then I get the jsonpath like:

'$[*] ? (@.fname=="Tiger" && @.flocation like_regex "Shenzhen, China, (86)" flag "i")'

When the statement contains '(' or ')', the regulation fails. In fact, for me, '(' or ')' is just a normal part of the condition. I tried to replace the '(' to '\(', but it doesn't work. I know why the statement is failed, but I don't know how to handle this kind of problem.

Pls give me some advice, thanks very much.