Overall, it depends your:
1. budget
2. the resolution you want to play at
3. the graphic settings
4. what you consider to be acceptable frame rates (FPS)
Here are some benchmarks for The Witcher 2 as reference. The Witcher 3 uses the same game engine as The Witcher; REDengine 3; but I am sure it has been updated since 2011 and has become a bit more demanding.
The MSI GP Series GP60 Leopard-836 linked by the above poster has a GeForce 940m graphics chip and a 1080p screen. That is a little less powerful than the GeForce GTX 660m so if you were to play The Witcher 2 you will get lower FPS compared to that graphics chip. The GeForce 940m would be good enough to play The Witcher 2 at 1366x768...