Label search function?

I've already tried a search function, that searches for my post headline. That works pretty well, but some people may search for different words. For example, I have a title named "Toaru Majutsu no Index". Some people may search for "To Aru Majutsu no Index", but that leads to no results. So I've made some labels for each post, but that didn't work in the search function. So could someone provide a code for a label search function?

My current code for the search function:

  Code:

<form id="searchthis" action="http://hitomitenshi.blogspot.com/search" style="display:inline;" method="get">
<input id="b-query" maxlength="500" name="q" size="24" type="text" />
<input id="b-searchbtn" value="Search" type="submit" />
</form>