Discord Bot won't reply to messages in channel

I'm not sure what is wrong with my python code, but I've been trying to get this to work wit ha bunch of different variations for a couple days now. The bot launches and goes online, but whenever I try to input a command into discord, the bot never responds. I've tried in multiple servers as well as my own. Here is my code:

import discord

client = discord.Client()


@client.event
async def on_ready():
    print('We have logged in as {0.user}'.format(client))


@client.event
async def on_message(message):
    if message.author == client.user:
        return

    if message.content.startswith('$hello'):
        await message.channel.send("Hello!")

client.run("original token would be here")