echo '<!--<pre>word_val = '; print_r($word_val); echo '-->';
//+сантехник
echo '<!--<pre>name = '; print_r($arr[$arr_key]['name']); echo '-->';
//Ковры+Сантехника
$arr[$arr_key]['name'] = preg_replace('#('.$word_val.')#ui', "<b>$1</b>", $arr[$arr_key]['name']);
Warning: preg_replace() [function.preg-replace]: Compilation failed: nothing to repeat at offset 1 in