This may already be known to you, but when I search for three letter words, all I have had to do is type an asterisk at the end of the word and it comes up.
For example Boa = Boa*, BCI = BCI*
The only downfall for this is that it doesn't work with two letter words and sometimes if the three letter word is part of longer word, then that shows up in the search. Ex: bin* will show results for bin and binder.
Just some search info.