In OpenVPN routing between the local networks (Win)

Good day dear friends, need help with routing between the local networks via OpenVPN.

There are 3 networks:
1. 10.6.*.*
2. 10.10*.*.*
3. 172.*.*.*

Network 10.6.*.* is media server have read access to all network's own optical channels to the given time between 10.6.*.* and 172.*.*.* optical channel partially out of order, and server access is difficult.

To solve the decision was made to run OpenVPN server which will be located in the network 10.10*.*.*, optical channel with 10.6.*.* works in a regular mode.

The question arose as to customers with a 172.*.*.* to get through the OpenVPN server 10.10*.*.*, on media server 10.6.*.*?
After the initial setup, clients with 172.*.*.* get from the OpenVPN server 10.10*.*.*, ip address 10.8.*.*.