Here are the Overwatch system requirements:
https://battle.net/support/article/7636
Truthfully your laptop isn't up to it, the laptops only really for office work. It's probably already struggling with Windows 10 as back in Win 7 time 4GB was the bare recommended RAM so really people should have 8GB for Win 10.
My parents laptop has pretty much the same specs as yours and god does it struggle with basic use.
I have a desktop with an i7, 16Gb RAM and a GTX 970, it plays Overwatch flawlessly because I installed parts that are specifically up to the task of gaming. Your Laptop wasn't built for gaming, it won't handle it and even if you tried you will be at a huge disadvantage as the other players are playing at the best settings, higher resolutions and at a much higher frame-rate.