I have experience OC'ing the 860m, though on a Acer Nitro.
You can use MSI afterburner, it is the best OC'ing tool for laptops. Just as a word of advice, increase the clock 10 MHz at a time (separately, first for core then for memory) and run a stress test (like MSI Kombustor) to check the stability. Then check the max combo that is staying stable and is not heating more than 85C. Should OC atleast 12 - 15%.
Keep us updated on how it went