If I get it correctly WordPress loads the search template dynamically by the parameters delivered to it. Specifically the s
parameter. Meaning if you try to send the user to the http://www.example.com/search.php
you’ll get 404 error page.
For now the only workaround I can think is to create a function which is hooked to the init
action hook that listens for a parameter in order to load the right file. The function must reside in the functions.php
of your theme (assuming you are developing a theme). The function goes like this:
function load_custom_search_template(){
if(isset($_REQUEST['custom_search'])){
require('my_search.php');
die();
}
}
add_action('init','load_custom_search_template');