If you know the IP ranges of your office/home networks then yes you can do this.
If you want to route only "port 80 & 443" traffic via the VPN then this is , in general,
not possible.
In order to redirect all traffic via the VPN except for local traffic , add something like this to the client config (or add it to the server config using "push .....":
redirect-gateway def1
route <LAN1-IP> <LAN1-NETMASK> net_gateway
route <LAN2-IP> <LAN2-NETMASK> net_gateway
where <LAN-IP> and <LAN-NETMASK> are for your local network. The term 'net_gateway' is an openvpn keyword.
