This is unlocked by progressing through the story and can not be missed.
Tips: In the corridor just before you reach him there is a health upgrade station, make sure to hack this. Steinman sometimes runs here to heal so if you hack it will poison him.
Lure him down into the water in the lower part of the surgery center and electric bolt him, then shoot at him, this will make this fight a lot shorter
OR,
If you decided to keep Incinerate!, there is an oil slick that is behind where he was standing to start, light this on fire to kill him faster, then when he goes to the water to put it out, keep shooting at him in the back to kill him quickly.
Hacking the security bot is also a major help.