One thing to consider. If you buy or lease your iPhone in a country that you are not a resident of, you will have to bring it back to that country to have it repaired or serviced as the warranty is only good in the country that you purchase it in.
With that said, you can check with any cellular provider to see what leasing options that are available to you. Apple has what is called an "iPhone Upgrade Program" but will require that you have an eligible U.S. credit card and requires a 24-month installment loan with a 0% interest from Citizens Bank, N.A. Getting that card may be problematic if you're not currently employed or show some form of income to be able to make the payments and you are not a U.S. citizen.