This is not currently possible. Wireless bridges require 802.11 frames to store 4 addresses (sender, receiver, destination and source), and standard 802.11 frames only store 3 addresses. While there are implementations of 4-address mode called [WDS](https://en.wikipedia.org/wiki/Wireless_distribution_system), they are [vendor-specific](https://wiki.openwrt.org/doc/howto/clientmode) and only supported on router hardware (meaning you should use hardware from the same vendor for this to work). On routers, the [command](http://askubuntu.com/questions/155041/bridging-loosing-wlan-network-connection-with-4addr-on-option-why) to enable WDS (and allow bridging of Wlan interfaces) mode is

    iw dev wlan0 set 4addr on

You can try it, but AFAIK it won't work on the RPi 3, at least not with built-in NIC. You may have some luck with USB adapters based on Atheros wireless chipsets. Until it does, you'll have to stick to NAT if you want to connect networks via RPi, as described [here](http://raspberrypi.stackexchange.com/questions/13440/bridge-wifi-and-ethernet). You can also try [Wlan kabel](https://github.com/escitalopram/wlan_kabel), but that's not real bridging either.

PS. I know the negative answer is not that useful, but we have lots of duplicate questions about bridging, and they can't be closed properly unless one of them is answered.