Yes, it’s possible. How exactly, it depends. If clients are using router as resolver and you simply have:
/ip dns
set allow-remote-requests=yes servers=192.168.0.7
Then it most likely won’t work, because from Adguard’s perspective, the client is router. There is some DNS extension that allows resolver to pass address of original client, but I doubt that RouterOS has that (plus Adguard would have to support it too).
But if you use (or you’d switch to) NAT-based redirection to Adguard, then you can see two possible solutions in this thread: http://forum.mikrotik.com/t/mikrotik-with-pi-hole-config-for-my-clients-ip-to-show-in-the-pi-hole-logs/159917/1