Well, there are more complex methods of doing this, but if your wanting just a quick fix kinda thing, how about using something like;
// start of scripts
$reg = lower(implode("|", explode(" ", $search)));
$q = mysql_query("SELECT * FROM pic WHERE lower(descript) REGEXP '".$reg."' OR lower(blurb) REGEXP '".$reg."'");
// rest of script
This saves time on a loop constructing a big long; $query .= " OR blah blah"; for each word in the search string, although personally I opt for alternate methods, these are perfectly viable and hold the basis of simple querying for keywords.