I am afraid this is a well known issue with the K16. Although the Bluetooth should operate on a standard protocol, and indeed the BMW unit is made by (I think) Cardo, you will never get a reliable, stable connection. Bmw have tweaked the Bluetooth configuration slightly to ensure that only their system will work reliably. Don't you love 'em!
It took me 2 different systems ( Schuberth and Cardo) before I gave up and went with the bmw unit.
Having said that I do think the bmw units are very good and I prefer them to the Schubert SRC. I have now used a pair of them for 25k miles.
Also, despite what bmw will tell you, they fit perfectly into the Schuberth C3 and C3 pro.
Max