try to replace the 61st line of the "search.php" script by the following 2 lines of code:
$searchstr = mysql_escape_string($_REQUEST['searchstr']);
$query = "SELECT * FROM " . $cMain['dbPrefix'] . "games WHERE title LIKE '%$searchstr%' OR MATCH(description) AGAINST ('$searchstr') OR keywords LIKE '%$searchstr%' LIMIT ".$cB["SEARCH"]["max"];