Searching a Category Keyword and getting no results?

I've got search set up on my site (blog). I also have categories integrated. When I search a word say the title of one of my blog posts it returns the correct results however if I search the name of one of the categories associated with that blog post it returns no results.

I wondered is it even possible to search categories using the search field and if so how would I add this to my current search?

Many thanks.