Use this app to trigger the full experience Google Now through the headset, not just the voice dialer part of it
(similar to Bluetooth Launch, but can unlock your phone and allows multiple searches too)
Version 1.03 brings improved second button press detection ("Fight for mic") and "Protect in Pocket" mode to prevent unwanted screen touches when phone is woken up in the pocket. Keyguard unlocking is reported to be fixed in v1.04 for Lollipopped Nexus users.
Ã”Ã»â•‘Start it and select if you want it to bypass your lock screen (swipe only, you cannot bypass security lock)
Ã”Ã»â•‘Press the button on the Hint
Ã”Ã»â•‘Select Hint2Search (NOT GOOGLE SEARCH!) in the "Complete action using..." dialog box
and that is it: you are good to go