Adding Key words to Switch

I gave you the syntax for the column. See tested code, FYI ... 

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Pc4xDsIwDAXQq3xl5hJVGWBDggVVHazWaSOSuCQOiNuTdOjgxf5+9jCYKyggMKuLCwi9dxwVpOjFWmbcV9nMeBrMY2Us5QeXQRHdpJKO/o10X6uzRRpU4swJWRPnvKeeUrDSh6GCXFnCWRoBW0srEXh2U2Uk5oO9cBK4uM+t86H5OVBSeJFXu1Mf2tMdvpL8DLH1tHsXxsayeTbj+Ac=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"How Injury Occurred" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"How Injury Occurred", type text}})
in
    #"Changed Type"

Adding two columns in DAX, you only need one. you can chose the one of your interest!

Source = 
SWITCH(
 TRUE(),
 CONTAINSSTRING([How Injury Occurred], "Client"), "Client",
 CONTAINSSTRING([How Injury Occurred], "Patient"), "Patient",
 CONTAINSSTRING([How Injury Occurred], "Doctor"), "Doctor",
 CONTAINSSTRING([How Injury Occurred], "Hero"), "Hero",
 "Something else"
)

Source 2 = 
SWITCH(
 TRUE(),
 SEARCH("Client",[How Injury Occurred],,-1)<>-1,  "Client",
 SEARCH("Patient",[How Injury Occurred],,-1)<>-1,  "Patient",
 SEARCH("Doctor",[How Injury Occurred],,-1)<>-1,  "Doctor",
 SEARCH("Hero",[How Injury Occurred],,-1)<>-1,  "Hero",
 "Something else"
) 

Final output:

Hope this helps!

Thanks for accepting the solution. 

Defintely you can add,

For "AND"  clause you can use "&&"

For "OR"  clause you can use "||"

For mix of AND and OR, use brackets and "&&" and "||"

Source = 
SWITCH(
 TRUE(),

   -- Searching for both words Client and Coffee
   CONTAINSSTRING([How Injury Occurred], "Client") 
        && CONTAINSSTRING([How Injury Occurred], "Coffee"), "Client - Coffee",

    -- Searching for word "guy"  and either of words Actor or Hero
    CONTAINSSTRING([How Injury Occurred], "guy")
       && (CONTAINSSTRING([How Injury Occurred], "Hero")
           || && CONTAINSSTRING([How Injury Occurred], "Actor"))
              , "Guy - Hero/Actor",

     -- To combine SEARCH and CONTAINSTRING
     CONTAINSSTRING([How Injury Occurred], "Doctor")
          && (SEARCH("medications",[How Injury Occurred],,-1)<>-1),  "Doctor - medications",

 "Something else"
)

DAX will get complicated. Try moving to M query if it gets out of hand.