You could ask your client to down save it for you. (File/Export/Legacy) That's your best bet. You might be able to open it in Acrobat, I'm not sure. If you are sure you don't have to make changes you could also open it in PhotoShop, just make sure you res is high enough. I'd recommend 300 dpi if it's only pics, and 1200 dpi if there is a lot of text.(600 dpi minimum. Of course I'm talking about for print.