One of the unique features on the LG G4 is its ability to display contacts from your registered online accounts when making searches from the Contacts app.
Before using this feature, you must first configure the online account on your smartphone (e.g. a Microsoft Exchange account). Go to Settings > General > Account and Sync and tap on Add Account. Select the type of account you want to add and fill in the required information (email address, incoming & outgoing mail server, credentials...).
Once the online account has been configured, simply open the Contacts app, tap on the Menu button and then on Contact Settings. Scroll to the General Info and tick the Online Search -Search contacts from online accounts as well when searching checkbox.
That's it; you can search for contacts from your online accounts directly from the Contacts app.