First, you should probably be looking for a position as a 'junior architect' - not 'intern' (or 'praktikant' or 'trainee'). As I understand it, most european schools require their students to do 6 months or a yearlong internship as part of their degree program, often unpaid. So, foreign 'interns' making 600 euro per month could be considered good money, in comparison, and might be acceptable if you're doing it for the experience or as a break from school.  That said, with 4+ years experience you are doing yourself a disservice by applying for internships and not a 'full time' architect position, which will pay a living wage. I met plenty of folks from South America when I was working in Europe.

Now, my rewards, please?

+ Evan.

Apply as a graduate architect, junior architect, or junior designer. Applying as an intern/praktikant/trainee gives the wrong impression (that you are still studying).

Already being in one of the cities you'd like to live in will go a long way. If you can save up a few months living expenses and just make the leap, (assuming of course that Argentina and Europe have some kind of working visa/holiday visa agreement), you would likely have a better chance. You can also then start to go to events in those cities, check out potential teaching spots at universities, and make some contacts. 

Best of luck!