No direct experience with this question, but years ago I had to find a Spanish-speaking driver (+car) at JFK for my in-laws. I Googled (in Spanish) some combination of Spanish, Hispanic, car service, Spanish speaker, etc. It worked well. Probably start with those terms for Portuguese. Boa sorte!!
Oops! Just saw "inside the baggage claim area..." that's a real challenge, it seems to me, but there may be ways to get special permission. Also contact the airline as they may have personnel inside security (including wheelchair operators) who speak Portuguese and can help.