Basically I have OpenVPN server and I would like to configure it so that clients that connect to OpenVPN are then connected to the Tor network on the server are able to browse hidden services and access clearnet via exit nodes. Is this possible, if so how? I am now running OpenVPN and Tor on CentOS.
The user will have to configure their browser to use the Tor on your VPN server as proxy with remote hostname resolution. Otherwise they can not browse hidden services.
You will probably need to create a transparent proxy (which uses socks to forward traffic via Tor), and have traffic routed through that. You will also need to do something funky with DNS, to stop clearnet DNS traffic leaking out of your VPN server.
So it's technically possible, but difficult. Some other systems exist which do this, for example http://onionwrt.link/ - it's not clear how they achieve this. NB: I don't fancy running their install script as root on my own device