What Bible verse talks about having faith like a child?

Matthew 18:3 (New World Translation) "and said: "Truly I say to you, Unless You turn around and become as young children, you will by no means enter into the kingdom of the heavens."

In addition, in the Jesus' society, be like a child was like to be nobody: a weak and needed creature which depends totally on its parents. Jesus state to "have faith like children", cause children are weak and needed, just like the Kingdom of God is: for the poor, the weak and hunger. For Jesus, God is for whose not have place in the society, these are the first for the Kingdom of God. When Jesus suggest to be like children, he is suggesting a change in the behavior of people, the beginning o a new personality.