SQL Server: Make all UPPER case to Proper Case/Title Case

CREATE FUNCTION [dbo].[fnConvert_TitleCase] (@InputString VARCHAR(4000) )
RETURNS VARCHAR(4000)
AS
BEGIN
DECLARE @Index INT
DECLARE @Char CHAR(1)
DECLARE @OutputString VARCHAR(255)

SET @OutputString = LOWER(@InputString)
SET @Index = 2
SET @OutputString = STUFF(@OutputString, 1, 1,UPPER(SUBSTRING(@InputString,1,1)))

WHILE @Index <= LEN(@InputString)
BEGIN
    SET @Char = SUBSTRING(@InputString, @Index, 1)
    IF @Char IN (' ', ';', ':', '!', '?', ',', '.', '_', '-', '/', '&','''','(')
    IF @Index + 1 <= LEN(@InputString)
BEGIN
    IF @Char != ''''
    OR
    UPPER(SUBSTRING(@InputString, @Index + 1, 1)) != 'S'
    SET @OutputString =
    STUFF(@OutputString, @Index + 1, 1,UPPER(SUBSTRING(@InputString, @Index + 1, 1)))
END
    SET @Index = @Index + 1
END

RETURN ISNULL(@OutputString,'')
END