While there are a lot of instructions available on the web on how to go about transferring info, this, i believe, is the fastest way you can have your contacts transferred from one device to another.
So far, when i checked for the integrity of the transferred contacts, it contains every info i had from the original device (postal/email address, birthdays, etc).
By the way, the app can transfer from: Apple to Apple; Android to Android; Apple to Android and vice versa. I am in no way connected to the developers of this app. I hope you enjoyed this guide.