Most of our clients out of the country pay by wire transfer.
Depending on their size they may or may not be familiar with this but it's not too bad of a process. They need some information about your bank, some routing numbers etc. and they can then wire money to you.
Depending on your invoice amounts, if they are lower and don't mind paying the ~2.5% - 3.0% you could accept credit cards. You could do this through PayPal Pro, stripe.com, square, or go a more traditional route and get a merchant / payment gateway from your local bank. Like using Authorize .Net.
I would recommend having a convenient way to process credit cards even id you don't do it for this client.