Unfortunately the Wiki search relies on the standard DNN search functionality, which is rather lacking

http://www.dotnetnuke.com/Resources/B... 

Hello Dave,

You may be want to have a look at our module Aricie.LuceneSearch that does just that.It replaces the native DNN search and extends the search data with additional info which you can then query to refine your search results.

If you want to try it out, there’s a trial version on our website and I think that it may be what you’re looking for. What’s more, we’ve built it to address what’s lacking in the DNN search system so you can extend it if the search engine doesn’t fit your needs out of the box.

I've just finished the DNN 6.1 compatibility tests and i am currently working on adding an autocomplete system so the product page will be updated soon, but don't hesitate to ask specific questions if you want to have more info.

Regards,

Samy