How to use Regex with spotlight
I’m assuming by “end with” you mean that files have the extension .jar or .doc. And given all those filenames, you want those who have “hello” in their filnames.

With that in mind, you’re looking for something like this:

(.jar AND “hello") OR (.doc AND “hello”)


Additionally, you could extend the number of “words” by adding: 

(.jar AND “hello” OR “some_other_word") OR (.doc AND “hello”)


For more ninja commands for Spotlight, your best bet is to read throughout this interesting doc from Apple, that’s the Spotlight’s Query Language documentation with lots of examples. 

Finally, if you want to know what attributes are available for you to query directly, refer to this blog post.