If you're asking if you can apply for fellowships before passing Step 3 I believe the answer is yes, however, I believe you can't graduate from an IM residency without passing all the USMLE Steps.
There is no law/rule/RRC/ACGME mandate for this. Many programs may require it, but not all. Some states require full licensure for the PGY-3 year, and those would certainly require Step 3.
To the OP, if you're asking if you can apply for fellowships if you attempted and failed step 3 (or if you attempted but don't have a score back), then yes you certainly can. Many people applying for fellowships (in their PGY-2) do not have Step 3 completed yet. If you failed Step 3, you might find that it will impact your interview offers.