You can use the Google voice search function provided by Google.
You can execute the mobile phone feature using LG Voice by pressing the Call button, when using a Bluetooth headset.
How to use Google voice search
Select Voice search in the Google folder or touch the Google voice icon on the right side of the Google search bar.
If you select Settings > Schedule > Google > Search and Now > Voice > OK Google detection > Always use, your voice will be recognized when the screen is turned on or off, or the mobile phone is charging.
How to use LG Voice
Register the Bluetooth headset that can use the microphone function using the Settings > Network > Bluetooth menu. Press the Call button on the headset and speak a voice command to activate the function.