title: I'd like to make my bot delete message containing one keyword
body: <p>I am trying to make my bot delete messages containing word "nom"
  how can I make my bot delete message if it's not starting with this word?
  actually this only works when the message starts with this word, and I don't know how to make it work everytime this word is in the message. I'd also like to make my bot delete it if someone tries to write something like ".nom", "NoM" etc. Can anyone help me?</p>
  
  <pre><code>@client.event
  
  async def on_message(message):
  
       if message.content == "nom":
  
            await client.delete_message(message)
  </code></pre>