Add category field to instant search

Hi there,

I am trying to implement this live search script in a WordPress project. It is working fine but I would like to add the ability to search a posts category as well. This requires me to reference the wp_terms (name and slug fields) as well as wp_posts. I am pretty green when it comes to this stuff – anyone able to shed some light?

Full Code as follows:

<?
         require_once(dirname(__FILE__).'/wp-config.php');	

	$config['maxresult'] = 10;				// Number of results to return
	$config['maxbodylength'] = 210;			// Trimming body length to x number of characters

	if (isset($_REQUEST['s']) && trim($_REQUEST['s'] != ""))
	{
		$searchstring = addslashes($_REQUEST['s']);
		if ($link = mysql_connect(DB_HOST, DB_USER, DB_PASSWORD))
		{
			if (mysql_select_db(DB_NAME, $link))
			{
					$storytable = $table_prefix . "posts";
					$titlefield = "post_title";
					$bodyfield = "post_content";
					$status = "post_status";
					$storyid = "guid";

				$stmt = "SELECT $bodyfield, $titlefield, $storyid, MATCH($bodyfield, $titlefield) AGAINST ('$searchstring*' IN BOOLEAN MODE) AS score FROM $storytable WHERE ($status = 'publish' OR $status = 'static') AND MATCH($bodyfield, $titlefield) AGAINST ('$searchstring*' IN BOOLEAN MODE) ORDER BY score DESC LIMIT " . $config['maxresult'];
				$searchstring = str_replace(" ", "% %", $searchstring);
				$stmt2 = "SELECT $bodyfield, $titlefield, $storyid FROM $storytable WHERE ($status = 'publish' OR $status = 'static') AND ($titlefield LIKE '%$searchstring%' OR $bodyfield LIKE '%$searchstring%') LIMIT " . $config['maxresult'];
				if ($result = mysql_query($stmt, $link))
				{
					if (mysql_num_rows($result) == 0)
					{
						$result = mysql_query($stmt2, $link);
					}
					if (mysql_num_rows($result) > 0)
					{
						echo "<ul>";
						while ($row = mysql_fetch_array($result, MYSQL_ASSOC))
						{
							// stripping images and links...
							$contents = stripslashes(strip_tags($row[$bodyfield]));
							if (strlen($contents) > $config['maxbodylength'])
								$contents = substr($contents, 0, $config['maxbodylength']) . "...";
							echo "<li><a href=\"$row[$storyid]\">" . $row[$titlefield] . "</a><p>$contents</p></li>";
						}
                                                      echo "</ul>";
					}
					else
						echo "<p class='error'>Sorry, no record matching your search criteria...</p>";
				}
				else
					echo "<p class='error'>Sorry, search is not available.</p>";
			}
			else
				echo "<p class='error'>Sorry, search is not available.</p>";
		}
		else
			echo "<p class='error'>Sorry, search is not available.</p>";
	}
?>