Error with restoring from a split .bak file with password
Below will work, as you had syntax error :

USE master
GO
RESTORE DATABASE client_a_database1
  FROM DISK = 'G:\database1\***.bak_1',
       DISK = 'G:\database1\***.bak_2',
       DISK = 'G:\database1\***.bak_3'
  WITH MOVE 'database1_data' TO 'G:\database1\***.mdf'
       MOVE 'database1_log' TO 'G:\database1\***.ldf', REPLACE,
  Password = 'password'
  GO 


Also, a RESTORE HEADERONLY output will help understand why you are getting - 


  restore was taken from a different MS SQL version.