Hi,
i have few subnets: 192.168.14.0/24 - LAN, 192.168.3.0/24 - WiFI (ubnt) and ...
Mikrotik CCR-1016-12G
Printer ip - 192.168.14.202
if i want setup printer on the client within 192.168.3.0/24, i have to specify ip address printer manually.
and if i want setup printer on the client within 192.168.14.0/24, it will find automatically
How configure mikrotik, so that printer is automatically within 192.168.3.0/24?
May be to use multicast?

1. create firewall forward rule which allows communication from 192.168.3.0/24 to host 192.168.14.202
2. do not forget to setup proper gateway on printer
3. add printer on customers' OS using printer's IP address (instead of searching for printer)

4. For security you can limit firewall rule to port used by printer (mostly TCP/9100) and icmp (for testing)

I had a similar issue as you. I have my printer, and other devices I do not trust, on a separate subnet at home.

Now the client my wife gets from her local IT at work have just started a automatic VPN tunnel that uses forced tunneling. This means she cannot use our printer at all as 0.0.0.0/0 point to the VPN endpoint and she cannot go outside the subnet the computer is on.

I solved this by adding a new IP for the router in the subnet I use. Let's say gateway is 192.168.0.1 I then added 192.168.0.2 for the router as well. Then I added a NAT (dst nat) rule that moves all traffic from 192.168.0.2 to the printer.
This solved the problem for me and as added bonus the computer can locate the printer just by scanning. Works like a charm.