Xperia Z2 :: Voice Control Via Inline Mic

Essentially what i'm trying to achieve is to be able to use Google voice commands from my Bose in-ear headphones while the phone is locked/sleeping. 
 
When on my way to and from work, I always have my headphones in and am listening to music. Answering calls is a breeze, simply tap the button on my inline mic and the call is answered. To make a call however, I need to take the phone out of my pocket, unlock the phone (using password) and then either use Google voice to place the call (but since i've made it this far and the phone is in my hand i usually just find the contact and make the call using my fingers). It would be ideal if I could simply activate the Google voice functions without taking the phone out of my pocket, unlocking, and then use the voice functionality to do a search or make a call. 
 
Currently when I hold down the button on my headphones and the phone is locked I get the message "to do a Google voice search, please unlock your phone". 
 
Ideally the functionality would be acessible without having to unlock the phone. Is there a setting I can change to add this? Are there specific headphones that alow this? Can I verbally give my password to unlock the phone and then use the voice functionality? 
 
The whole goal here is to not have to take the phone out of my pocket and manually enter my password.