Click the links below to access phonological awareness and articulation games.
https://www.quia.com/pages/havemorefun.html
https://www.quia.com/pages/speechersclass.html
For tongue twisters, click the link below.
http://learnenglishkids.britishcouncil.org/tongue-twisters
S and SH tongue twisters are in the attachment below: