Assume you saved adb path into your Windows environment path
Activate debug mode in Android
Connect to PC via USB
Open command prompt type: adb tcpip 5555
Disconnect your tablet or smartphone from pc
Open command prompt type: adb connect IPADDRESS
(IPADDRESS is the DHCP/IP address of your tablet or smartphone, which you can find by Wi-Fi -> current connected network)
Now in command prompt you should see the result like: connected to xxx.xxx.xxx.xxx:5555