I looked into this for you and I found that the PUT IT ON LAY-BUY gateway is available in Argentina, which is a form of offering partial payments or instalments.
For a full list of payment gateways available in Argentina, you can see our supported gateways page here.
Could you tell me a little bit more about your products and why you're looking to have partial payments on your store? That way if the above option does not suit you, I could try help you look for alternatives! If you do not yet have a Shopify store, you should also checkout our FAQ page here that will help you learn more and get started.
Let me know if you have any other questions!