Note: I assume your wireless interface is wlan1 and your primary ethernet interface is ether1.
In winbox open a new terminal and paste the following commands ...
/ip address add address=172.18.115.142/32 network=172.18.115.13 broadcast=172.18.115.13 interface=wlan1 comment="PTP Link to Highsite"
/ip address add address=172.18.115.142/28 interface=ether1 comment="LAN Range"
/ip route add dst-address=172.16.0.0/12 gateway=172.18.115.13 comment="Route to WUG"
Your adapter settings in windows should look something like:
IP Address 172.18.115.129
Primary DNS 172.18.1.1
Secondary DNS 126.96.36.199 (or whatever DNS you got from your ISP)
If you want to add a static route open command prompt as administrator and run the following command:
route add 172.16.0.0 mask 255.240.0.0 172.18.115.142 -p