this will add your path to include path
uses [man]ini_set[/man]
it willl get current include_path,
add and append your path (only temporary for your script)
and ini_set the new include path
//
$mypath = "./includes"; // your subfolder
ini_set ( 'include_path', ini_get( 'include_path' ) . ';' . $mypath );
// for windows use as above, semicolon
// for linux use colon ... ':' . $mypath
//