function wildcard_in_array ($string, $array = array ())
			{       
			    foreach ($array as $key => $value) {
			        unset ($array[$key]);
			        if (strpos($value, $string) !== false) {
			            $array[$key] = $value;
			        }
			    }       
			    return $array;
			}

// use
$key = key(wildcard_in_array('string', $array));