Question [Q] use wifi for LAN and 3g for Internet?

is there a way to use the wifi network just for lan and the 3g network for internet at the same time?

i'll explain my issue:
when i connect my phone to my odb2 dongle using wifi i can use the odb2 interface but i have no access to internet...
while driving i'd like to record my car activity and use internet as well.

so i need wifi on to connect to the odb2 (but no internet access)
and 3g to use internet at the same time.

i've googled it but unsuccesfully.

do you have any suggestion?

ps: my device is a note3 (unrooted)