SSRS, Visual Studio 2015, IIF statement using Or

Question

Trying to figure out what is wrong with the following IIF statement:

=iif((Field1 <> "String1" Or "String2") 
    Or ( Field2 <> "String1" Or "String2")
    Or ( Field3 <> "String1" Or "String2")
    Or (Field 4 <> "String 3"), Field5, nothing)

Essentially I am wanting to filter out rows that meet iif, but when ever I try to I get the warning

[rsRuntimeErrorInExpression] The Value expression for the textrun ‘Field.Paragraphs[0].TextRuns[0]’ contains an error: Input string was not in a correct format.

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Answer 1

=iif((Field1 <> "String1" Or Field1 <> "String2") 
    Or ( Field2 <> "String1" Or  Field2 <> "String2")
    Or ( Field3 <> "String1" Or Field3 <> "String2")
    Or (Field 4 <> "String 3"), Field5, nothing)